In the production of hydrocarbons from earth formations, wellbores are drilled into reservoirs or pay zones. Such wellbores are completed and perforated at one or more zones to recover hydrocarbons from reservoirs. Many oil and gas wells produce fluid from underground formations containing solid particles, which are loose and/or not strongly attached to each other and when hydrocarbon-containing fluid is produced, it tends to carry entrained solids with it. These solids can cause serious damage to well equipment due to erosion. Erosion is particularly bad when a disproportionate amount of flow is concentrated in a relatively small region, resulting in high velocities of the solids. These regions are called “hot spots”.
Filters, normally called sand screens of various designs, and slotted liners are commonly placed opposite the formation and below the production tubing in the well bore preventing entry of solid particulates into the tubing. Filters of different makes and configurations are commonly used as solids control devices. Filters currently available in the art typically erode substantially over time. In addition, they cannot effectively produce all zones because of the fact that the pressure differential required varies over the zones, which creates “hot spots” as mentioned above. Furthermore, there is currently no method available of filter cleaning by circulation of fluids, with or without additives, outside the filter.
Filters are commercially available that are made of multiple layers of woven material sintered together into a porous rigid medium, however they are only available in several mesh sizes with only one mesh size available per filter, and they are subject to corrosion and/or erosion.
There is a great need in the art for a solid filter assembly that is resistant to all erosive chemicals and production fluids known in the petroleum industry to cause problems and that can deal effectively with all sizes of solids to optimize production, even where optimal production requires different permeabilities and porosities of the filter for different intervals vertically or radially. It would constitute a great advance in the art if the same filter assembly were designed such that well intervention and cleaning were possible by circulation at the outside of the filter.